cmd/containerboot: speed up tests (#14883)

The test suite had grown to about 20s on my machine, but it doesn't
do much taxing work so was a good candidate to parallelise. Now runs
in under 2s on my machine.

Updates #cleanup

Change-Id: I2fcc6be9ca226c74c0cb6c906778846e959492e4
Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>

cmd/containerboot/tailscaled.go

@@ -38,11 +38,11 @@ func startTailscaled(ctx context.Context, cfg *settings) (*local.Client, *os.Pro
 	}
 	log.Printf("Starting tailscaled")
 	if err := cmd.Start(); err != nil {
-		return nil, nil, fmt.Errorf("starting tailscaled failed: %v", err)
+		return nil, nil, fmt.Errorf("starting tailscaled failed: %w", err)
 	}
 
 	// Wait for the socket file to appear, otherwise API ops will racily fail.
-	log.Printf("Waiting for tailscaled socket")
+	log.Printf("Waiting for tailscaled socket at %s", cfg.Socket)
 	for {
 		if ctx.Err() != nil {
 			return nil, nil, errors.New("timed out waiting for tailscaled socket")